Sheet straightening and tensioning apparatus

ABSTRACT

Apparatus for tensioning the edge of a sheet of flexible material, comprising two clips each capable of gripping a corner of the sheet, and means for mounting and controlling the clips so that they move between a first position wherein the clips lie side-by-side at a first loading station to one side of the centreline of the apparatus, and a second position wherein the clips lie side-by-side at a second loading station to the other side of the centreline of the apparatus, and, during each successive movement between the first and second positions, a third position wherein the clips are separated in positions substantially symmetrical about the centreline.

llnited States Patent Hall Feb. 12, 1974 1 SHEET STRAIGHTENING AND 3,376,036 4/1968 Weir 38/143 TENSIONING APPARATUS 3,421,756 l/l969 Weir 38/143 3,657,832 4/1972 Valentine 38/143 [75] Inventor: Roger Smith Hall, Thll'Sk, England [73] Assignee: Baker Perkins Jaxons Limited, Primary ExaminerGeo. V. Larkin Glasgow, Scotland Attorney, Agent, or FirmStevens, Davis, Miller & 22 Filed: Aug. 24, 1972 M0511 21 A 1. No.: 283 413 1 pp 57 ABSTRACT [30] Foreign Application Priority Dam Apparatus for tensioning the edge of a sheet of flexi- 1 ble material, comprismg two clips each capable of Sept. 8, 1971 Great Britain 419 1/71 g pp g a comer of the sheet, and means for m0unt ing and controlling the clips so that they move beg? 'i tween a first position wherein the clips lie side-by-side 'l I45 54 at a first loading station to one side of the centreline 1 0 l 6 of the apparatus, and a second position wherein the clips lie side-by-side at a second loading station to the other side of the centreline of the apparatus, and, dur- [56] References Cited ing each successive movement between the first and UNITED STATES PATENTS second positions, a third position wherein the clips are 3,258,866 7/1966 Bates 271/45 X separated in positions substantially symmetrical about 3,729,846 5/1973 well the cent eline 3,664,046 5/1972 Thompson 3,604,132 9/1971 Thompson 38/143 5 Claims, 5 Drawing Figures Patented Feb. 12, 1974 3 Sheets-Sheet 1 -lll atented Feb. 152, 197

3 Sheets-Sheet 5 SHEET STRAIGHTENING AND TENSIONING APPARATUS This invention relates to apparatus for tensioning the edge of a sheet of flexible material before application of the sheet to a rotary drum. The inventionis particu larly concerned with the handling of washed sheets during the feed'ofthese to automatic ironing equipment.

Apparatus is known wherein the two corners of the edge of a sheet may be held in clips which are caused to move apart on a beam so that the edge of the sheet is straightened and tensioned between the clips. The beam is mounted adjacent to a rotary feed member having vacuum ports on its surface, and the apparatus is controlled so that when the edge of the sheet is tensioned the clips release the sheet and vacuum is applied to the ports so that the edge of the sheet is held to the rotary feed member. This member can then carry the sheet to a conveyor which in turn feeds the sheet to a calender for ironing the sheet.

There are two known forms of such apparatus. In one of these there is only a single clip movable between a loading station at one end of the beam and a remote station. An operator loads one corner of the sheet into the clip, and manually holds the other corner while the clip moves to the remote station. In the second form two clips are provided, movable between a loading station at the centre of the beam and spaced remote stations. The operator then loads both clips and the sheet is straightened and tensioned between the clips. The capacity of existing calender apparatus is such that an operator working either of the above forms of apparatus is not keeping the calender at its full working capacity, which is of course disadvantageous.

According to the present invention apparatus for tensioning the edge of a sheet of flexible material comprises two clips and means for mounting and controlling the clips so that they move between a first position wherein the clips lie side-by-side at a first loading station to one side of the centreline of the apparatus, and a second position wherein the clips lie side-by-side at a second loading station to the other side of the centreline of the apparatus, and, during each successive movement between the first and second positions, a third position wherein the clips are separated in positions substantially symmetrical about the centreline.

This enables the apparatus to be fed by two operators, one at each loading station. Thus, the corners of a firstsheet are loaded into the clips at the first loading station, the leading edge of the sheet is straightened and tensioned as the clips move to the third position and is removed from the clips in that position, and the empty clips move on to the second position. There a second sheet is loaded into the clips, the clips move back to the third position to straighten and tension the leading edge,'the sheet is removed from the clips and the empty clips return to the first position. During the interval that the clips are away from the first or second loading station the operator at that station can be preparing a subsequent sheet for loading. The apparatus can thus speed up the feed of sheets into the calender, so enabling this device to be operated more efficiently.

Preferably the two clips are mounted on a beam for movement between the centre of the beam and opposite ends of the beam, and the beam is mounted so that it may be moved bodily between limit positions wherein the centre of the beam lies to either side of the centreline of the apparatus, i.e., at either of the two loading stations. Movement of the clips and the beam are then coordinated so that the clips are together at the centre of the beam when this is at either of its limit positions, and are separated at the ends of the beam as the centre of the beam is coincident with the centreline of the apparatus.

Conveniently the beam is pivotally mounted at the ends of two parallel arms in turn pivotally mounted to the frame of the apparatus. Pivotal movement of the arms will thus move the beam longitudinally of the apparatus. Where the sheet is to be removed from the clips to a rotary feed member the feed member is conveniently positioned below, and with its axis parallel to, the beam, and the pivotally mounted arms extend horizontally, with the pivotal axes being vertical. Thus, apart from the longitudinal movement of the beam relative to the feed member there will also be lateral movement away from the beam on moving from the centre position to either loading station, which is advantageous in assisting to prevent loading from interfering with the feed member.

Alternatively the beam may be pivoted at the end of vertically disposed parallel arms, or the beam may be mounted for reciprocation without any lateral movement. I

In a preferred construction the beam carries a fluidoperated piston and cylinder arrangement, the piston of which is secured to the two ends of a length of wire running round pulleys at each end of the beam and having the clips secured to opposite runs of the wire. Movement of the piston in the cylinder will thus cause movement of the clips in opposite directions. Other means of moving the clips along the beam may alternatively be employed.

In order that the invention may bebetter understood a specific embodiment thereof will'now be described with reference to the accompanying drawings in which:

FIGS. 1 and 2 show plan views of the apparatusin two alternative positions;

FIG. 3 is a schematic view of part of the apparatus; and

FIGS. 4 and 5 are respectively enlarged plan and elevation views of part of the apparatus.

As shown in the drawings the apparatus comprises a frame 1 rotatably supporting a feed member 2 having vacuum parts in its surface, and to the interior of which a vacuum may be applied byline 3. Feed members of this form are well known and may, for example, be as described in United Kingdom Patent Specification No. 1,194,] 88.

The frame has two parallel arms 4 and 5 pivotally mounted thereon about vertical pivots 6 and 7. At their free ends the arms are pivoted about vertical axes 8 and 9 to a beam 10 extending parallel to the axis of the feed member 2, and lying above the feed member. Means are provided for moving the arms so that the beam may move from a position wherein its centre lies on the centreline of the apparatus as shown in FIG. 1, either to a position where its centre is at a first loading station A as shown in solid lines in FIG. 2 or a position where its centre is at a second loading station B as shown in dotted lines in FIG. 2.

The beam is shown in more detail in FIGS. 4 and 5 and comprises a centre member 11, two end plates such as 12 and four longitudinal rods joining the end plates and passing through the centre member. Three of these rods are shown in FIGS. 4 and 5 as 13, 14 and 15. Mounted on the beam are two clips 16 and 17, the clip 16 being guided for movement longitudinally of the beam by a guide sleeve 18 on the left hand part of rod 13, and the clip 17 being similarly guided by a guide sleeve 19 on the right hand part of rod 14. The two clips are similar in construction (clip 17 is shown with parts removed) and each have conventional pneumatic holding and spring release means controlling a movable member capable of securing a corner of a sheet to the clip.

Secured between the end plate 12 and the member 11 is a double-acting cylinder 20 in which works a piston 21. Secured to opposite sides of the piston are the free ends of a wire 22 which passes around a pulley 23 on the end plate 12 and around a similar pulley on the opposite plate, to form with the piston an endless loop having first and second runs 24 and 25. The clip 16 is secured to the first run 24 of the wire and the clip 17 is secured to the second run 25 of the wire. With the piston 21 in the position shown in FIG. 3 the two clips lie side-by-side at the centre of the beam. If the piston is moved to right as seen in FIG. 3 it will be seen that the two clips move in opposite directions towards the ends of the beam.

Operation of the apparatus will now be readily understood. Assume that the apparatus is initially as shown in solid lines in FIG. 2, i.e., with the clips 16 and 17 lying side-by-side at loading station A. An operator at that station places corners of a sheet under the clips and presses down the clips. The clips, as is known, incorporate valves responsive to this action to hold the clips closed by pneumatic pressure. The closing action is also utilised as a signal to the arm moving means, so that the arms 4 and 5 pivot anticlockwise. At the same time, pressure is applied to the cylinder 20 to move the piston 21 to the right and so cause the clips 16, 17 to move apart. These actions are timed and interlocked so that the clips reach their fully extended position as the beam centre coincides with the centre line of the apparatus as shown in FIG. 1. As this happens, vacuum is applied to the feed member 2, and the clips are released so that the sheet is freed from the clips and held by the feed member. The arms 4 and 5 continue to swing anticlockwise, and the air pressure to cylinder 20 is reversed so that the clips 16 and 17 are driven together again. The clips reach the centre of the beam as the beam reaches the dotted line position of FIG. 2, so that the clips are presented side-by-side at loading station B. An operator at that station loads a sheet into the clips and the arms swing back clockwise, the clips separating and releasing the sheet at the centre position of the beam, and then coming back together as the beam again comes to rest with its centre at loading station A.

It will be understood that the necessary pneumatic and electrical control and sequencing means are incorporated in the apparatus, and their design will be readily obvious to one skilled in the art.

What I claim is:

1. Apparatus for tensioning the edge of a sheet of flexible material, comprising two clips each capable of gripping a corner of the sheet, clip-mounting means and clip-controlling means controlling said clips so that they move between a first position wherein the clips lie side-by-side at a first loading station to one side of the centreline of the apparatus, and a second position wherein the clips lie side-by-side at a second loading station to the other side of the centreline of the apparatus, and, during each successive movement between the first and second positions, a third position wherein the clips are separated in positions substantially symmetrical about the centreline.

2. Apparatus according to claim 1 and including a beam, said clip-mounting means mounting said two clips on said beam for movement between the centre of the beam and opposite ends of the beam, means for moving said clips on said beam, and beam-mounting means mounting said beam so that it may be moved bodily between a first limit position wherein the centre of said beam lies to a first side of the centreline of the apparatus and a second limit position wherein the centre of said beam lies to a second side of the centreline of the apparatus, said clip-controlling means being operative to coordinate the movement of said clips and said beam so that said clips are in said first position when together at the centre of the beam with the beam in said first limit position, said clips are in said second position when together at the centre of said beam with said beam in said second limit position, and said clips are in said third position when separated at opposite ends of said beam with the centre of said beam substantially coincident with the centreline of the apparatus.

3. Apparatus according to claim 2 wherein said apparatus includes a frame and said beam-mounting means includes first and second parallel arms, means pivotally mounting a first end of each arm to said frame and means pivotally mounting a second end of each arm to a respective end of said beam.

4. Apparatus according to claim 3 in which said first and second arms each extend horizontally and said pivot means each have vertical pivot axes.

5. Apparatus according to claim 2 in which said means for moving said clips on said beam comprises a fluid-operated piston and cylinder arrangement, said cylinder being secured to said beam, first and second pulleys mounted at opposite ends of said beam, and a length of wire running around said pulleys and secured to said piston, said clips being secured to opposite runs of said wire. 

1. Apparatus for tensioning the edge of a sheet of flexible material, comprising two clips each capable of gripping a corner of the sheet, clip-mounting means and clip-controlling means controlling said clips so that they move between a first position wherein the clips lie side-by-side at a first loading station to one side of the centreline of the apparatus, and a second position wherein the clips lie side-by-side at a second loading station to the other side of the centreline of the apparatus, and, during each successive movement between the first and second positions, a third position wherein the clips are separated in positions substantially symmetrical about the centreline.
 2. Apparatus according to claim 1 and including a beam, said clip-mounting means mounting said two clips On said beam for movement between the centre of the beam and opposite ends of the beam, means for moving said clips on said beam, and beam-mounting means mounting said beam so that it may be moved bodily between a first limit position wherein the centre of said beam lies to a first side of the centreline of the apparatus and a second limit position wherein the centre of said beam lies to a second side of the centreline of the apparatus, said clip-controlling means being operative to coordinate the movement of said clips and said beam so that said clips are in said first position when together at the centre of the beam with the beam in said first limit position, said clips are in said second position when together at the centre of said beam with said beam in said second limit position, and said clips are in said third position when separated at opposite ends of said beam with the centre of said beam substantially coincident with the centreline of the apparatus.
 3. Apparatus according to claim 2 wherein said apparatus includes a frame and said beam-mounting means includes first and second parallel arms, means pivotally mounting a first end of each arm to said frame and means pivotally mounting a second end of each arm to a respective end of said beam.
 4. Apparatus according to claim 3 in which said first and second arms each extend horizontally and said pivot means each have vertical pivot axes.
 5. Apparatus according to claim 2 in which said means for moving said clips on said beam comprises a fluid-operated piston and cylinder arrangement, said cylinder being secured to said beam, first and second pulleys mounted at opposite ends of said beam, and a length of wire running around said pulleys and secured to said piston, said clips being secured to opposite runs of said wire. 